Hi,

I'm getting a code 53 (system overvoltage at battery or at EGR) . I am having symptoms of stuck open EGR. Won't idle, runs very rough, and runs best over 40 mph. I can see the egr nestled away safely under the plenum. Is there some way to get to the underside of it to see if it is stuck open, by feeling for the position of the diaphragm? Can I test voltage at the solenoid somehow, to see if it has too much when the key is on ?

Thanks

mechanic - avoider

------------------
88 GTA 5.7 TPI Charcoal Grey Bone Stock except for loose muffler which makes it a bit louder than normal.

 

GTA 88,

Under your ignition coil on the passenger side, you'll see two hard vacuum lines going into a rubber 90* block. This block connects to the EGR solenoid. The front line goes to the bottom of your throttle body (vacuum source), the rearward line goes to the valve itself.

You'll need a handheld vacuum pump/gauge. Apply vacuum to that rearward line (goes to EGR valve under plenum). You should be able to get 20" without bleeding off. Now, with the vaccum still applied, go start the car and it should bleed off. Now get a mirror and get it under the plenum at an angle that you can see the EGR pintle. As you apply vacuum, it should suck up. If this is how it operates, your EGR valve is ok and you should be relieved that you don't have to pull your plenum/runners for a stupid valve!

Now you're ready to check your solenoid. With the key off, apply vacuum to the inlet side of the solenoid (line from the TB). You should be able to hold vacuum without bleedoff. If your passing vacuum in this state, the solenoid is toast. If not, continue diagnosing.

Short the ALDL terminal A-B with the key in the on position. Now try to apply vacuum to the solenoid. If vacuum passes (and didn't before), your solenoid is ok. If it doesn't pass vacuum still, disconnect the electrical connector and use a test light between the two terminals. If its lit, the solenoid is bad. Good luck bro!

------------------
-Jason M. 1991 Camaro Z28

 

Jason,

Thanks! I will try those steps as soon as I can, and will be back on the board with the results and/or more questions.
I would be soooo great if the solenoid is bad, and all I have to do is slap in a new solenoid, code 53 bye bye, car running right again. Even if the egr and the sol pass, at least I'll know I can stop worrying about that possibility and go on to the next likely candidate. I feel like the guy lost in the forest and wondering if I should backtrack and take a different path. The way out could be just around the next corner, but maybe not....

 

But what if the valve is stuck open just a little bit from carbon deposits or something? How could the test shown above diagnose this?

 

Well, if the EGR effect is like my other car, opening it a little will not cause the horrible running and no idle that I have. If it is the EGR causing my prob, it seems it would have to be stuck at least half way open. And if the solenoid is bad, it might be putting out full voltage, making it stick wide open.
A lot of people think my prob is in the charging system, a bad alternator or a bad ground somewhere. I am hoping it is the EGR solenoid, which would be simpler to deal with than tracking down a bad connection.


------------------
88 GTA 5.7 TPI Charcoal Grey Bone Stock except for loose muffler which makes it a bit louder than normal.